What is tungsten carbide coating?
Tungsten carbide (WC) coating is a type of thermal spray coating in which particles of tungsten carbide, one of the hardest engineering materials known, are deposited onto the part surface within a cobalt- or nickel-based metallic matrix. Ranking among the hardest materials after diamond, WC provides exceptional protection for surfaces exposed to abrasive flow, sand and hard-particle contact.
How is it applied?
Tungsten carbide coating is typically applied by HVOF (High Velocity Oxy-Fuel). Powdered WC-Co or WC-Co-Cr alloy is heated in a combustion chamber and propelled onto the part surface at supersonic speed (above Mach 1). This high velocity produces a very dense, low-porosity coating (typically below 1%), which is the main reason for its high bond strength.
Typical technical values
| Property | Typical value |
|---|---|
| Hardness | 1100–1300 HV (Vickers) |
| Coating thickness | 100–400 microns |
| Bond strength | Above 68 MPa |
| Porosity | Below 1% |
WC-Co or WC-Co-Cr?
There are two main variants: WC-Co (pure cobalt matrix) and WC-Co-Cr (chromium-alloyed matrix). The chromium addition improves oxidation/corrosion resistance in corrosive or humid environments, which is why WC-Co-Cr is preferred in most industrial applications. For a detailed comparison, see our article The Difference Between WC-Co and WC-CoCr.
Which parts is it used on?
Tungsten carbide coating is particularly favoured for drilling equipment, PDC bit bodies, sand and slurry pumps, hydraulic cylinders, valve seating surfaces and the internal surfaces of fluidised-bed equipment. In the oil & gas, mining and energy sectors, almost every moving part operating in an abrasive environment benefits from this coating.
Advantages over alternative methods
Compared with conventional methods such as case hardening or chrome plating, tungsten carbide coating offers higher wear resistance and is an environmentally less problematic process (compared with the hexavalent chromium compounds used in hard chrome plating). In addition, coating thickness and alloy composition can be flexibly adjusted to the part's operating conditions.
Frequently Asked Questions
How long does tungsten carbide coating take?
It depends on the part size and the surface area to be coated; for small to medium parts, coating and final grinding can usually be completed within a few days.
Is any further processing required after coating?
Yes — on functional surfaces, final tolerance and surface roughness are almost always achieved by precision grinding. For details, see our article Grinding After Coating.
Let Us Assess Your Tungsten Carbide Coating Requirement
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